This is a report of the first four cases of left ventricle aneurysm of the posterior and inferior segments successfully treated surgically in the Hospital de Cardiología y Neumología del Centro Médico Nacional, México D. F., and represent the twelve per cent of all realized aneurysmectomies. The patients were all men with 57 years mean age, and a previous history of posteroinferior myocardial infarction, complicated in three of them with angor and severe ventricle arrythmias; chest X ray in lateral view showed a bump of the posteroinferior border of the cardiac silhouette; the echocardiography increase in the ventricular diameter below the mitral valve; the ventriculography made evident a diastolic bulging with systolic expansion of posterior and inferior segments of the left ventricle and no mitral regurgitation; selective coronary arteriography showed a dominant right pattern with 100 per cent proximal occlusion. Aneurysmectomy was done in all four cases and aortocoronary by-pass in two. The posteromedial papilar muscle was found respected in all cases and in two cases a mural thrombus was detected.